fix indentation in dbt tests alerts code examples

[japerry911]

Hello team,

I was receiving the follow error with current indentation examples:

Parsing Error
  Invalid test config given in models/staging/airbyte_salesforce/stg__airbyte_salesforce_account.yml:
        test definition dictionary must have exactly one key, got [('not_null', None), ('meta', {'description': 'Not NULL test for Fax.'})] instead (2 keys)
        @: UnparsedModelUpdate(original_file_path='mode...ne)

I have updated the applicable spots.

Also, when should tests be updated to data_tests in docs? I know we use data_tests now with 1.8.x dbt core.

Thank you 🚀

[haritamar]

Thanks for the fix @japerry911 !